Heavy-Duty P Series Cam Brakes

Transcription

1 Maintenance Manual MM-0440 Heavy-Duty P Series Cam Brakes Issued 09-04

2 Service Notes About This Manual This manual provides maintenance and service information for Meritor heavy-duty P Series cam brakes. Before You Begin 1. Read and understand all instructions and procedures before you begin to service components. 2. Read and observe all Warning and Caution hazard alert messages in this publication. They provide information that can help prevent serious personal injury, damage to components, or both. 3. Follow your company s maintenance and service, installation, and diagnostics guidelines. 4. Use special tools when required to help avoid serious personal injury and damage to components. Hazard Alert Messages and Torque Symbols How to Obtain Product and Service Information On the Web Visit the DriveTrain Plus by Meritor Tech Library at meritor.com to easily access product and service information. The Library also offers an interactive and printable Literature Order Form. Meritor s Customer Service Center Call Meritor s Customer Service Center at Technical Electronic Library on CD The DriveTrain Plus by Meritor Technical Electronic Library on CD contains product and service information for most Meritor and Meritor WABCO products. $20. Specify TP How to Obtain Tools and Supplies Call Meritor s Commercial Vehicle Aftermarket at to obtain Meritor tools and supplies. WARNING A Warning alerts you to an instruction or procedure that you must follow exactly to avoid serious personal injury and damage to components. CAUTION A Caution alerts you to an instruction or procedure that you must follow exactly to avoid damage to This symbol alerts you to tighten fasteners to a specified torque value. Information contained in this publication was in effect at the time the publication was approved for printing and is subject to change without notice or liability. Meritor Heavy Vehicle Systems, LLC, reserves the right to revise the information presented or to discontinue the production of parts described at any time. Meritor Maintenance Manual MM-0440 (Issued 09-04)

3 Contents pg. pg. i Asbestos and Non-Asbestos Fibers 1 Section 1: Exploded View 2 Section 2: Introduction Description Cam Brake Tips 3 Section 3: Removal and Disassembly Removal Wheel Components 4 Brake Shoes Camshaft and Slack Adjuster 5 Section 4: Prepare Parts for Assembly Clean, Dry and Inspect Parts Clean and Dry Parts Corrosion Protection Inspect Parts 8 Section 5: Assembly and Installation Installation Camshaft Assemblies 9 Brake Shoes Slack Adjusters 12 Section 6: Adjustment Adjust the Brakes Measure Free Stroke 13 Commercial Vehicle Safety Alliance (CVSA) Guidelines 15 Section 7: Reline the Brakes Reline the Brakes Installing Linings with Rivets 16 Installing Linings with Bolts Oversize Drums 17 Section 8: Maintenance Lubrication Brake Assembly Components 19 Slack Adjuster Intervals Applications Adjust the Brakes 20 Reline the Brakes Important Information on Linings and Primary Shoe Locations 21 Major Overhaul Inspection Before You Return the Vehicle to Service 22 Section 9: Specifications Torque Specifications

4 Asbestos and Non-Asbestos Fibers Figure 0.1 ASBESTOS FIBERS WARNING The following procedures for servicing brakes are recommended to reduce exposure to asbestos fiber dust, a cancer and lung disease hazard. Material Safety Data Sheets are available from Meritor. Hazard Summary Because some brake linings contain asbestos, workers who service brakes must understand the potential hazards of asbestos and precautions for reducing risks. Exposure to airborne asbestos dust can cause serious and possibly fatal diseases, including asbestosis (a chronic lung disease) and cancer, principally lung cancer and mesothelioma (a cancer of the lining of the chest or abdominal cavities). Some studies show that the risk of lung cancer among persons who smoke and who are exposed to asbestos is much greater than the risk for non-smokers. Symptoms of these diseases may not become apparent for 15, 20 or more years after the first exposure to asbestos. Accordingly, workers must use caution to avoid creating and breathing dust when servicing brakes. Specific recommended work practices for reducing exposure to asbestos dust follow. Consult your employer for more details. Recommended Work Practices 1. Separate Work Areas. Whenever feasible, service brakes in a separate area away from other operations to reduce risks to unprotected persons. OSHA has set a maximum allowable level of exposure for asbestos of 0.1 f/cc as an 8-hour time-weighted average and 1.0 f/cc averaged over a 30-minute period. Scientists disagree, however, to what extent adherence to the maximum allowable exposure levels will eliminate the risk of disease that can result from inhaling asbestos dust. OSHA requires that the following sign be posted at the entrance to areas where exposures exceed either of the maximum allowable levels: DANGER: ASBESTOS CANCER AND LUNG DISEASE HAZARD AUTHORIZED PERSONNEL ONLY RESPIRATORS AND PROTECTIVE CLOTHING ARE REQUIRED IN THIS AREA. 2. Respiratory Protection. Wear a respirator equipped with a high-efficiency (HEPA) filter approved by NIOSH or MSHA for use with asbestos at all times when servicing brakes, beginning with the removal of the wheels. 3. Procedures for Servicing Brakes. a. Enclose the brake assembly within a negative pressure enclosure. The enclosure should be equipped with a HEPA vacuum and worker arm sleeves. With the enclosure in place, use the HEPA vacuum to loosen and vacuum residue from the brake parts. b. As an alternative procedure, use a catch basin with water and a biodegradable, non-phosphate, water-based detergent to wash the brake drum or rotor and other brake parts. The solution should be applied with low pressure to prevent dust from becoming airborne. Allow the solution to flow between the brake drum and the brake support or the brake rotor and caliper. The wheel hub and brake assembly components should be thoroughly wetted to suppress dust before the brake shoes or brake pads are removed. Wipe the brake parts clean with a cloth. c. If an enclosed vacuum system or brake washing equipment is not available, employers may adopt their own written procedures for servicing brakes, provided that the exposure levels associated with the employer s procedures do not exceed the levels associated with the enclosed vacuum system or brake washing equipment. Consult OSHA regulations for more details. d. Wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA for use with asbestos when grinding or machining brake linings. In addition, do such work in an area with a local exhaust ventilation system equipped with a HEPA filter. e. NEVER use compressed air by itself, dry brushing, or a vacuum not equipped with a HEPA filter when cleaning brake parts or assemblies. NEVER use carcinogenic solvents, flammable solvents, or solvents that can damage brake components as wetting agents. 4. Cleaning Work Areas. Clean work areas with a vacuum equipped with a HEPA filter or by wet wiping. NEVER use compressed air or dry sweeping to clean work areas. When you empty vacuum cleaners and handle used rags, wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA for use with asbestos. When you replace a HEPA filter, wet the filter with a fine mist of water and dispose of the used filter with care. 5. Worker Clean-Up. After servicing brakes, wash your hands before you eat, drink or smoke. Shower after work. Do not wear work clothes home. Use a vacuum equipped with a HEPA filter to vacuum work clothes after they are worn. Launder them separately. Do not shake or use compressed air to remove dust from work clothes. 6. Waste Disposal. Dispose of discarded linings, used rags, cloths and HEPA filters with care, such as in sealed plastic bags. Consult applicable EPA, state and local regulations on waste disposal. Regulatory Guidance References to OSHA, NIOSH, MSHA, and EPA, which are regulatory agencies in the United States, are made to provide further guidance to employers and workers employed within the United States. Employers and workers employed outside of the United States should consult the regulations that apply to them for further guidance. NON-ASBESTOS FIBERS WARNING The following procedures for servicing brakes are recommended to reduce exposure to non-asbestos fiber dust, a cancer and lung disease hazard. Material Safety Data Sheets are available from Meritor. Hazard Summary Most recently manufactured brake linings do not contain asbestos fibers. These brake linings may contain one or more of a variety of ingredients, including glass fibers, mineral wool, aramid fibers, ceramic fibers and silica that can present health risks if inhaled. Scientists disagree on the extent of the risks from exposure to these substances. Nonetheless, exposure to silica dust can cause silicosis, a non-cancerous lung disease. Silicosis gradually reduces lung capacity and efficiency and can result in serious breathing difficulty. Some scientists believe other types of non-asbestos fibers, when inhaled, can cause similar diseases of the lung. In addition, silica dust and ceramic fiber dust are known to the State of California to cause lung cancer. U.S. and international agencies have also determined that dust from mineral wool, ceramic fibers and silica are potential causes of cancer. Accordingly, workers must use caution to avoid creating and breathing dust when servicing brakes. Specific recommended work practices for reducing exposure to non-asbestos dust follow. Consult your employer for more details. Recommended Work Practices 1. Separate Work Areas. Whenever feasible, service brakes in a separate area away from other operations to reduce risks to unprotected persons. 2. Respiratory Protection. OSHA has set a maximum allowable level of exposure for silica of 0.1 mg/m3 as an 8-hour time-weighted average. Some manufacturers of non-asbestos brake linings recommend that exposures to other ingredients found in non-asbestos brake linings be kept below 1.0 f/cc as an 8-hour time-weighted average. Scientists disagree, however, to what extent adherence to these maximum allowable exposure levels will eliminate the risk of disease that can result from inhaling non-asbestos dust. Therefore, wear respiratory protection at all times during brake servicing, beginning with the removal of the wheels. Wear a respirator equipped with a high-efficiency (HEPA) filter approved by NIOSH or MSHA, if the exposure levels may exceed OSHA or manufacturers recommended maximum levels. Even when exposures are expected to be within the maximum allowable levels, wearing such a respirator at all times during brake servicing will help minimize exposure. 3. Procedures for Servicing Brakes. a. Enclose the brake assembly within a negative pressure enclosure. The enclosure should be equipped with a HEPA vacuum and worker arm sleeves. With the enclosure in place, use the HEPA vacuum to loosen and vacuum residue from the brake parts. b. As an alternative procedure, use a catch basin with water and a biodegradable, non-phosphate, water-based detergent to wash the brake drum or rotor and other brake parts. The solution should be applied with low pressure to prevent dust from becoming airborne. Allow the solution to flow between the brake drum and the brake support or the brake rotor and caliper. The wheel hub and brake assembly components should be thoroughly wetted to suppress dust before the brake shoes or brake pads are removed. Wipe the brake parts clean with a cloth. c. If an enclosed vacuum system or brake washing equipment is not available, carefully clean the brake parts in the open air. Wet the parts with a solution applied with a pump-spray bottle that creates a fine mist. Use a solution containing water, and, if available, a biodegradable, non-phosphate, water-based detergent. The wheel hub and brake assembly components should be thoroughly wetted to suppress dust before the brake shoes or brake pads are removed. Wipe the brake parts clean with a cloth. d. Wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA when grinding or machining brake linings. In addition, do such work in an area with a local exhaust ventilation system equipped with a HEPA filter. e. NEVER use compressed air by itself, dry brushing, or a vacuum not equipped with a HEPA filter when cleaning brake parts or assemblies. NEVER use carcinogenic solvents, flammable solvents, or solvents that can damage brake components as wetting agents. 4. Cleaning Work Areas. Clean work areas with a vacuum equipped with a HEPA filter or by wet wiping. NEVER use compressed air or dry sweeping to clean work areas. When you empty vacuum cleaners and handle used rags, wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA, to minimize exposure. When you replace a HEPA filter, wet the filter with a fine mist of water and dispose of the used filter with care. 5. Worker Clean-Up. After servicing brakes, wash your hands before you eat, drink or smoke. Shower after work. Do not wear work clothes home. Use a vacuum equipped with a HEPA filter to vacuum work clothes after they are worn. Launder them separately. Do not shake or use compressed air to remove dust from work clothes. 6. Waste Disposal. Dispose of discarded linings, used rags, cloths and HEPA filters with care, such as in sealed plastic bags. Consult applicable EPA, state and local regulations on waste disposal. Regulatory Guidance References to OSHA, NIOSH, MSHA, and EPA, which are regulatory agencies in the United States, are made to provide further guidance to employers and workers employed within the United States. Employers and workers employed outside of the United States should consult the regulations that apply to them for further guidance. Meritor Maintenance Manual MM-0440 (Issued 09-04) i

5 1 Exploded View 1 Exploded View Figure a Item Description 1 Camshaft and Chamber Bracket 2 Bracket Capscrews 3 Bracket Lock Washers 4 Bracket-to-Spider Spacer 5 Manual Slack Adjuster 6 Cam Spacing Washer 7 Cam Head Washer 8 Small Spacing Washer 9 Cam Needle Bearing 10 Shoe and Lining Assembly 11 Anchor Pin Lock Screw 12 Brake Spider 13 Brake Shoe Anchor Pin 14 Anchor Pin Lock 15 Anchor Pin Felt Retainer 16 Anchor Pin Felt 17 Shoe Return Spring Item Description 18 Double Head Cam 19 Clevis Pin 20 Cotter Pin 21 Chamber Stud Nut 22 Chamber Stud Washer 23 Air Chamber Meritor Maintenance Manual MM-0440 (Issued 09-04) 1

6 2 Introduction 2 Introduction Description Meritor P Series cam brakes are air actuated and cam operated with two brake shoes each mounted on a separate anchor. The brakes are designed for heavy-duty on- or off-highway applications and special equipment where larger shoe and drum areas are necessary. Brake diameters of inches and 22-inches are available with automatic or manual adjustment. The brakes can be assembled with auxiliary spring brakes. Figure 2.1. Figure 2.1 Figure 2.1 Cam Brake Tips Air Chambers HEAVY-DUTY P SERIES BRAKE b To ensure correct brake balance, all brake chambers on the same axle must be the same size and type to help ensure a balanced brake system for maximum lining wear and drum life. Brake Kits Meritor brake shoes, rollers, camshafts and shoe return springs are designed to perform as a system. Always install original equipment manufacturer spec-level components during maintenance or when you upgrade from standard to long-life brakes to help ensure correct brake performance and maximum lining life. Cam Heads Cam heads can look the same, but that doesn t mean they will perform the same in your brake system. Two cam head profiles can appear to be identical, but very small differences in cams from different manufacturers can be significant enough to affect the performance of your brakes. To ensure a balanced brake system and optimum lining and drum life, always install the correct replacement cam. Cam Rollers To avoid flat spots, lubricate a cam roller directly in the web roller pocket and not at the cam-to-roller contact area. Flat spots can affect brake adjustment and result in premature brake wear or reduced braking performance. Drums To help ensure balanced braking, even lining and drum wear, and correct function of the automatic slack adjuster, do not install a cast drum and a composite drum on the same axle. A cast drum and a composite drum each absorbs and dissipates heat differently. When drum types and weights are mixed, different rates of heat absorption and dissipation occur that can affect the brake system. Hardware When you service cam brakes, replace all the springs, anchor pins, bushings and rollers not just the shoe return springs to help ensure maximum braking performance. Linings Insist on the same brand of quality original equipment manufacturer friction lining material to help ensure fewer relines and compatibility with your present system. Replacement Parts Always use original equipment manufacturer quality standard parts. Meritor brakes work as a system, and when you replace original parts with will-fit parts, you can compromise the performance of the entire system. Return Springs Replace cam brake return springs at every cam brake reline. The return spring is critical to alignment, accurate return of the brake away from the drum and correct automatic slack adjustment. Trailer Cam Brakes Long-life bushings require correct lubrication for maximum performance and bushing life. Although you do not have to replace spider cam bushings on trailer axles as frequently, Meritor recommends that you lubricate the bushings at least four times during the life of your brake lining. Automatic Slack Adjusters Automatic doesn t mean maintenance-free. Correctly installed and lubricated automatic slack adjusters help to ensure maximum brake system performance. Never mix automatic slack adjusters on the same axle. When you replace automatic slack adjusters, always use replacement parts that were originally designed for the brake system to help ensure even brake wear, balanced braking and maximum brake performance. 2 Meritor Maintenance Manual MM-0440 (Issued 09-04)

7 3 Removal and Disassembly 3 Removal and Disassembly Hazard Alert Messages Read and observe all Warning and Caution hazard alert messages in this publication. They provide information that can help prevent serious personal injury, damage to components, or both. WARNING To prevent serious eye injury, always wear safe eye protection when you perform vehicle maintenance or service. ASBESTOS AND NON-ASBESTOS FIBERS WARNING Some brake linings contain asbestos fibers, a cancer and lung disease hazard. Some brake linings contain non-asbestos fibers, whose long-term effects to health are unknown. You must use caution when you handle both asbestos and non-asbestos materials. Removal Wheel Components WARNING Park the vehicle on a level surface. Block the wheels to prevent the vehicle from moving. Support the vehicle with safety stands. Do not work under a vehicle supported only by jacks. Jacks can slip or fall over. Serious personal injury and damage to components can result. 1. Park the vehicle on a level surface. Block the wheels to prevent the vehicle from moving. 2. Use a jack to raise the vehicle so that the wheels to be serviced are off the ground. Support the vehicle with safety stands. WARNING Before you service a spring chamber, carefully follow the manufacturer s instructions to compress and lock the spring to completely release the brake. Verify that no air pressure remains in the service chamber before you proceed. Sudden release of compressed air can cause serious personal injury and damage to components. NOTE: For complete maintenance and service information on Meritor automatic slack adjusters, refer to Maintenance Manual 4, Cam Brakes and Automatic Slack Adjuster. To obtain this publication, refer to the Service Notes page on the front inside cover of this manual. If the slack adjuster is not a Meritor automatic slack adjuster, refer to the manufacturer s literature for the correct service procedures. 4. Fully release the slack adjusters so the shoes retract and the drums will clear the linings. CAUTION You must disengage a pull pawl or remove a conventional pawl before rotating the manual adjusting nut, or you will damage the pawl teeth. A damaged pawl will not allow the slack adjuster to automatically adjust brake clearance. Replace damaged pawls before putting the vehicle in service. Figure 3.1 A. Disengage the pawl. If the slack adjuster has a pull pawl: Use a screwdriver or equivalent tool to pry the pull pawl at least inch (0.8 mm) to disengage the teeth. Figure 3.1. If the slack adjuster has a conventional pawl: Remove the pawl assembly, pressure relief capscrew, spring and pawl, from the side of the slack adjuster housing. Figure 3.2. CONVENTIONAL PAWL Figure 3.1 PULL PAWL PAWL PRY UP b 3. If the brake has spring chambers, carefully cage and lock the spring, so that the spring cannot actuate during assembly. Meritor Maintenance Manual MM-0440 (Issued 09-04) 3

8 3 Removal and Disassembly Figure 3.2 Figure 3.3 MANUAL ADJUSTING NUT LOCK SCREWS a Figure 3.2 B. Use a wrench to turn the manual adjusting nut CLOCKWISE until the brake shoes are fully retracted, and the lining clears the drum. C. Install the pawl into the slack adjuster housing. 5. Follow the manufacturer s instructions to remove the wheel and drum from the axle. Brake Shoes PAWL ASSEMBLY 1. Remove the brake shoe return springs a 2. Remove the lock rings, retainers and felt seals from the anchor pins. 3. Cut the lock wire and remove the anchor pin lock screws from the brake spider. Figure 3.3. Figure Remove the anchor pins and the brake shoe assemblies. Camshaft and Slack Adjuster 1. Remove the two clevis pins from the clevis on the air chamber push rod. 2. Remove the slack adjuster from the camshaft. 3. Check the up-and-down and side-to-side end play of the camshaft. Figure 3.4. If end play exceeds XX.XX, replace the needle bearings. Use a press with the correct size driver to remove the needle bearing assemblies. Figure " (0.76 MM) a Figure Remove the washers, retainers and spacers from the camshaft. 5. Pull the camshaft from the spider and bracket. 4 Meritor Maintenance Manual MM-0440 (Issued 09-04)

9 4 Prepare Parts for Assembly 4 Prepare Parts for Assembly Hazard Alert Messages Read and observe all Warning and Caution hazard alert messages in this publication. They provide information that can help prevent serious personal injury, damage to components, or both. WARNING To prevent serious eye injury, always wear safe eye protection when you perform vehicle maintenance or service. ASBESTOS AND NON-ASBESTOS FIBERS WARNING Some brake linings contain asbestos fibers, a cancer and lung disease hazard. Some brake linings contain non-asbestos fibers, whose long-term effects to health are unknown. You must use caution when you handle both asbestos and non-asbestos materials. Clean, Dry and Inspect Parts Clean and Dry Parts WARNING Solvent cleaners can be flammable, poisonous and cause burns. Examples of solvent cleaners are carbon tetrachloride, and emulsion-type and petroleum-base cleaners. Read the manufacturer s instructions before using a solvent cleaner, then carefully follow the instructions. Also follow the procedures below. Wear safe eye protection. Wear clothing that protects your skin. Work in a well-ventilated area. Do not use gasoline, or solvents that contain gasoline. Gasoline can explode. You must use hot solution tanks or alkaline solutions correctly. Read the manufacturer s instructions before using hot solution tanks and alkaline solutions. Then carefully follow the instructions. CAUTION Do not use hot solution tanks or water and alkaline solutions to clean ground or polished parts. Damage to parts can result. Corrosion Protection 1. If you assemble parts immediately after you clean them, lubricate parts with grease to prevent corrosion. Parts must be clean and dry before you lubricate them. Do not apply grease to the brake linings or the brake drums. 2. If you store parts after you clean them, apply a corrosion-preventive material. Do not apply the material to the brake linings or the brake drums. Store parts in a special paper or other material that prevents corrosion. Inspect Parts 1. Check the spider for expanded anchor pin holes and for cracks. Replace damaged spiders and anchor pin bushings. 2. Check the camshaft bracket for broken welds, cracks and correct alignment. Replace damaged brackets. 3. Check the anchor pins for corrosion and wear. Replace worn or damaged anchor pins. 4. Check the brake shoes for rust, expanded rivet holes, broken welds and correct alignment. Replace a shoe with any of the above conditions. 5. Check the camshaft for cracks, wear and corrosion. Check the cam head, bearing journals and splines. Replace worn or damaged camshafts. 6. Inspect the large and small clevis pins for wear and damage. Replace worn or damaged parts. CAUTION Always replace used clevis pin retainer clips with new ones when you service an automatic slack adjuster or chamber. Do not reuse retainer clips. Discard used clips. When you remove a retainer clip, it can bend or gap apart and lose retention. Damage to components can result. NOTE: If you remove cotter pins from a slack adjuster during maintenance and service procedures, Meritor recommends that you install clevis pin retainer clips at assembly. 7. Inspect the clevis pin retainer clips or cotter pins for wear and damage. Replace worn or damaged retainer clips and cotter pins. Do not reuse clevis pin retainer clips. Always replace used retainer clips with new ones. Discard used clips. Use soap and water to clean non-metal parts. Dry parts immediately after cleaning with soft, clean paper or cloth, or compressed air. Meritor Maintenance Manual MM-0440 (Issued 09-04) 5

10 4 Prepare Parts for Assembly WARNING Do not operate the vehicle with the brake drum worn or machined beyond the discard dimension indicated on the drum. The brake system may not operate correctly. Damage to components and serious personal injury can result. CAUTION Replace the brake drum if it is out-of-round. Do not turn or rebore a brake drum, which decreases the strength and capacity of the drum. Damage to components can result. 8. Use the following procedure to inspect the brake drums. A. Check the brake drums for cracks, severe heat checking, heat spotting, scoring, pitting and distortion. Replace drums as required. Do not turn or rebore brake drums, which decreases the strength and heat capacity of the drum. B. Measure the inside diameter of the drum in several locations with a drum caliper or internal micrometer. Figure 4.1. If the diameter exceeds the specifications supplied by the drum manufacturer: Replace the drum. 2. Check the clevis pins, clips and bushing in the slack adjuster arm for wear and damage. Replace worn or damaged parts. Check the bushing diameter to ensure it does not exceed inch (13.5 mm). If the bushing diameter exceeds inch (13.5 mm): Replace the bushing. CAUTION You must disengage a pull pawl or remove a conventional pawl before rotating the manual adjusting nut, or you will damage the pawl teeth. A damaged pawl will not allow the slack adjuster to automatically adjust brake clearance. Replace damaged pawls before putting the vehicle in service. NOTE: When you service an automatic slack adjuster with a conventional pawl, replace the conventional pawl with a pull pawl. 3. Disengage the pull pawl. Use a screwdriver or equivalent tool to pry the pull pawl at least 1/32-inch (0.8 mm) to disengage the teeth. Figure 4.2. Figure 4.2 If the slack adjuster has a conventional pawl: Remove the pawl. Figure 4.2. PAWL Figure 4.1 CONVENTIONAL PAWL PULL PAWL PRY UP b Figure 4.2 Figure Check the dust shields for wear and damage. Repair or replace worn or damaged parts as necessary. Slack Adjusters a 1. If the slack adjuster has a quick connect clevis, check the gap between the clevis and the collar. If the gap exceeds inch (1.52 mm): Replace the clevis with a one-piece threaded clevis. CAUTION You must turn the adjusting nut COUNTERCLOCKWISE when you check gear torque on an automatic slack adjuster. If you turn the adjusting nut incorrectly, you will damage the pawl teeth. A damaged pawl will prevent the slack adjuster from automatically adjusting the clearance between the linings and drum. Damage to components can result. 4. Check manual slack adjusters by rotating the adjustment nut of the worm shaft to verify that the worm drive is free. Figure 4.3. Replace the slack adjuster if the worm drive does not operate correctly. Do NOT repair a manual slack adjuster. 6 Meritor Maintenance Manual MM-0440 (Issued 09-04)

11 4 Prepare Parts for Assembly Figure 4.3 If the slack adjuster has a conventional pawl: Install the pawl assembly into the housing. Tighten the capscrew to lb-ft (16-23 N ADJUSTMENT NUT NOTE: If necessary, install a camshaft into the slack adjuster gear to minimize grease flow through the gear holes. 7. Use a grease gun to apply Meritor specification O-616-A, O-692 or O-645 lubricant to the slack adjuster grease fitting, until grease flows from around the camshaft splines and pawl assembly. Refer to Section 8 for more lubricant information a Figure Use a lb-in torque wrench and turn the adjusting nut COUNTERCLOCKWISE to rotate the gear 360 degrees, or 22 turns of the wrench, as you read the torque scale on the wrench. The value should be less than 25 lb-in (2.83 N m) as you rotate the gear. Figure 4.4. If the torque value is less than 25 lb-in (2.8 N m) as you rotate the gear: The slack adjuster is operating correctly. If the torque value exceeds 25 lb-in (2.8 N m) as you rotate the gear: Replace the slack adjuster. Figure TURNS ROTATE GEAR 360 Figure a 6. Re-engage the pull pawl. Remove the screwdriver or equivalent tool. The pull pawl will re-engage automatically. Meritor Maintenance Manual MM-0440 (Issued 09-04) 7

12 5 Assembly and Installation 5 Assembly and Installation Hazard Alert Messages Read and observe all Warning and Caution hazard alert messages in this publication. They provide information that can help prevent serious personal injury, damage to components, or both. Figure 5.2 WARNING To prevent serious eye injury, always wear safe eye protection when you perform vehicle maintenance or service. ASBESTOS AND NON-ASBESTOS FIBERS WARNING Some brake linings contain asbestos fibers, a cancer and lung disease hazard. Some brake linings contain non-asbestos fibers, whose long-term effects to health are unknown. You must use caution when you handle both asbestos and non-asbestos materials. Figure 5.3 Figure a Installation Camshaft Assemblies 1. Tighten all the spider bolts to the specified torque. Figure 5.1. Figure 5.1 SEAL LIP CAMSHAFT BRACKET SEAL LIP SPIDER a Figure 5.3 BOLT SIZE 7/16"-20 1/2"-20 9/16"-18 5/8"-18 T TORQUE LB-FT LB-FT LB-FT LB-FT N m N m N m N m a 3. If necessary, install new cage and needle bearing assemblies. 4. If the camshaft bracket was removed, install the gasket and bracket to the spider. Tighten the capscrews to the correct torque as specified in Section Install the cam head thrust washer onto the camshaft. Apply Meritor specification O-617-A or O-617-B grease to the camshaft needle bearings and journals. 6. Install the camshaft through the spider and bracket so that the camshaft turns freely by hand. Figure 5.4. Figure Install new camshaft seals into the spider and camshaft bracket with a seal driver. Figure 5.2. Install both seals with their lips toward the slack adjuster. Figure Meritor Maintenance Manual MM-0440 (Issued 09-04)

13 5 Assembly and Installation Figure 5.4 Figure 5.5 Check end play a a Figure 5.4 Brake Shoes NOTE: Meritor recommends that you replace the springs, rollers and anchor pins at each reline. When the brake is disassembled, or when necessary, lubricate the anchor pins and rollers where these parts touch the brake shoes. Do not allow grease to contact the area of the camshaft roller that touches the camshaft head. Figure Install a new camshaft lock ring. 5. Connect the slack adjuster to the air chamber push rod. Manual Slack Adjusters 1. If the clevis was not replaced, install new clevis pins. 2. Install and adjust the slack adjuster to match the Brake Slack Adjuster Position (BSAP). Figure Lubricate the camshaft roller pin and anchor pin with Meritor specification O-617-A or O-617-B grease. 2. Install the brake shoes onto the spider with the anchor pins. Verify that the flat sides of the anchor pins are aligned with the lock screw holes in the spider. 3. Install the anchor pin felt seals, retainers and lock rings. 4. Install the anchor pin lock screws and tighten to lb-ft ( N m). Install the lock wire for the lock 5. Install new shoe return springs. Slack Adjusters 1. Apply Meritor specification O-637 or other rust preventive grease to the camshaft splines. 2. Install the slack adjuster spacer washer on the splined end of the camshaft followed by the slack adjuster. 3. Add spacer washers to limit the slack adjuster end play to inch (1.5 mm) maximum. Figure 5.5. Meritor Maintenance Manual MM-0440 (Issued 09-04) 9

14 5 Assembly and Installation Figure 5.6 Figure AND BRACKET OFFSET BSAP ± Color of Template Part Number Applications Dark brown TP-4786 Truck or tractor drum brake Tan TP-4787 Trailer drum brake White TP-4781 Coach drum brake SLACK LENGTH CORRECT POSITION OF MANUAL SLACK ADJUSTER 3.750" AND 3.812" OFFSETS ONLY (FOR OTHER BRACKET OFFSETS, REFER TO THE VEHICLE MANUFACTURER S SPECIFICATIONS) SLACK ADJUSTMENT SIZE ± BSAP a Figure 5.7 CAMSHAFT CENTER Measure the slack adjuster arm length b 2. Remove the pawl assembly and align the slack adjuster arm with the clevis. Turn the manual adjusting nut to the left until the clevis pin hole in the slack adjuster arm is aligned with the large hole in the clevis. Assemble with the large clevis pin and fasten with a cotter pin. Figure 5.8 and Figure 5.9. Figure 5.6 Automatic Slack Adjusters 1. If you install the same slack adjuster that was removed, install the clevis on the push rod in the position you marked when you removed the clevis. Check the position of the clevis with the Installation template. Figure 5.7. If you are installing a new slack adjuster: Verify it is the same length as the one you are replacing. Install the clevis on the push rod. Check the position of the clevis with the Installation template. Figure 5.7. Figure 5.8 MANUAL ADJUSTING NUT PAWL ASSEMBLY a Figure Meritor Maintenance Manual MM-0440 (Issued 09-04)

15 5 Assembly and Installation Figure 5.9 CLEVIS LARGE CLEVIS PIN AND RETAINER CLIP ACTUATOR ROD LARGE CLEVIS PIN RETAINER CLIP P/N 2257-D-1174 SMALL CLEVIS PIN RETAINER CLIP P/N 2257-C-1173 SMALL CLEVIS PIN AND RETAINER CLIP The clevis pin retainer clips must be fully installed and positioned around the SIDE of the clevis pin a Figure Pull on the actuator rod until the hole in the top of the rod is aligned with the small hole in the clevis. Install the small clevis pin and fasten with a cotter pin. 4. Install the pawl assembly. 5. Apply the brakes and permit the push rods to extend fully. There must be clearance between the slack adjuster and all chassis components. NOTE: Refer to Maintenance Manual 4, Cam Brakes and Automatic Slack Adjuster, for complete installation instructions. 6. Release the brakes and verify that the manual adjusting nut rotates to the left as the push rods fully retract. Meritor Maintenance Manual MM-0440 (Issued 09-04) 11

16 6 Adjustment 6 Adjustment Hazard Alert Messages Read and observe all Warning and Caution hazard alert messages in this publication. They provide information that can help prevent serious personal injury, damage to components, or both. WARNING To prevent serious eye injury, always wear safe eye protection when you perform vehicle maintenance or service. Before you service a spring chamber, carefully follow the manufacturer s instructions to compress and lock the spring to completely release the brake. Verify that no air pressure remains in the service chamber before you proceed. Sudden release of compressed air can cause serious personal injury and damage to components. ASBESTOS AND NON-ASBESTOS FIBERS WARNING Some brake linings contain asbestos fibers, a cancer and lung disease hazard. Some brake linings contain non-asbestos fibers, whose long-term effects to health are unknown. You must use caution when you handle both asbestos and non-asbestos materials. Adjust the Brakes Measure Free Stroke When you perform preventive maintenance procedures on an in-service brake, check both the free stroke and adjusted chamber stroke. Refer to the procedures in this section. Free stroke sets the clearance between the linings and drum. The in-service free stroke may be slightly longer than inch ( mm) specified in this procedure. This is acceptable if the adjusted chamber stroke is within the limits shown in Table A and Table B. CAUTION You must disengage a pull pawl or remove a conventional pawl before rotating the manual adjusting nut, or you will damage the pawl teeth. A damaged pawl will not allow the slack adjuster to automatically adjust brake clearance. Replace damaged pawls before putting the vehicle in service. 1. Disengage a pull pawl. Use a screwdriver or equivalent tool to pry the pull pawl at least 1/32-inch (0.8 mm) to disengage the teeth. If the slack adjuster has a conventional pawl: Remove the pawl. 2. Use a wrench to turn the adjusting nut COUNTERCLOCKWISE until the brake shoes contact the drum. Figure 6.1. Then back off the adjusting nut 1/2 turn in the opposite direction. Figure 6.1 Figure Measure the distance from the center of the large clevis pin to the bottom of the air chamber while the brake is released. The measurement you obtain is X in Figure 6.2. Figure 6.2 Figure 6.2 Y X MEASURE FREE STROKE Disengage pawl e FREE STROKE = Y MINUS X Drum brake free stroke must be " ( mm). Disc brake free stroke must be " ( mm) a 4. Use a pry bar to move the slack adjuster and position the linings against the drum, brakes applied. Measure the same distance again while the brakes are applied. The measurement you obtain is Y in Figure Meritor Maintenance Manual MM-0440 (Issued 09-04)

17 6 Adjustment CAUTION Do not set free stroke shorter than inch ( mm) for drum brakes. If the measurement is too short, linings can drag. Damage to components can result. 5. Subtract X from Y to obtain the in-service free stroke. The measurement must be inch ( mm) for drum brakes. Figure 6.2. If the free stroke measurement is not within specification: Turn the adjusting nut to adjust free stroke. Figure 6.3. Follow the steps above to check free stroke again, until the measurement is within specification. Commercial Vehicle Safety Alliance (CVSA) Guidelines Measure Push Rod Travel or Adjusted Chamber Stroke Use the following procedure to check in-service push rod travel or adjusted chamber stroke on truck and tractor brakes. NOTE: Hold the ruler parallel to the push rod and measure as carefully as possible. A measurement error can affect CVSA re-adjustment limits. CVSA states that any brake 1/4-inch or more past the re-adjustment limit, or any two brakes less than 1/4-inch beyond the re-adjustment limit, will be cause for rejection. Figure 6.3 SHORTEN STROKE Disengage pull pawl or remove conventional pawl. LENGTHEN STROKE a 1. The engine must be OFF. If the brake has a spring chamber, follow the manufacturer s instructions to release the spring. Verify that no air pressure remains in the service section of the chamber. 2. Verify that pressure is 100 psi (689 kpa) in the air tanks. Determine the size and type of brake chambers on the vehicle. 3. With the brakes released, mark the push rod where it exits the chamber. Measure and record the distance. Have another person apply and hold the brakes on full application. Figure 6.4. Figure 6.3 Figure Re-engage the pull pawl by removing the screwdriver or equivalent tool. The pull pawl will re-engage automatically. Step 1 Mark push rod here to measure stroke. If the slack adjuster has a conventional pawl: Install the pawl assembly into the housing. Tighten the capscrew to lb-ft (16-23 N 7. If the brakes have spring chambers, carefully release the springs. Test the vehicle before you return it to service. Spring brakes released Service brakes not applied Step 2 Step 3 STROKE psi ( kpa) in air tank engine OFF Spring brakes released Service brakes applied b Figure 6.4 Meritor Maintenance Manual MM-0440 (Issued 09-04) 13

18 6 Adjustment 4. Measure the push rod travel or adjusted chamber stroke from where the push rod exits the brake chamber to your mark on the push rod. Measure and record the distance. Figure Subtract the measurement you recorded in Step 3 from the measurement you recorded in Step 4. The difference is the push rod travel or adjusted chamber stroke. 6. Refer to Table A or Table B to verify that the stroke length is correct for the size and type of air chambers on the vehicle. If push rod travel or adjusted chamber stroke is greater than the maximum stroke shown in Table A or Table B: Inspect the slack adjuster and replace it, if necessary. Alternate Method to Measure Push Rod Travel or Adjusted Chamber Stroke Use the CVSA procedure, except in Step 3 and Step 4, measure the distance from the bottom of the air chamber to the center of the large clevis pin on each of the brakes. CVSA North American Out-of-Service Criteria Reference Tables Information contained in Table A and Table B is for reference only. Consult the CVSA s Out-of-Service Criteria Handbook for North American Standards, Appendix A. Visit their website at to obtain the handbook. Table A: Standard Stroke Clamp-Type Brake Chamber Data Brake Type Outside Diameter (inches) Adjustment Limit (inches) 6 4-1/2 1-1/ /4 1-3/ /16 1-3/ /8 1-3/ /32 1-3/ /32 1-3/ / /4 Table B: Long Stroke Clamp-Type Brake Chamber Data Brake Type Outside Diameter (inches) Adjustment Limit (inches) / / / * 7-7/ / *For 3" maximum stroke type 24 chambers. 14 Meritor Maintenance Manual MM-0440 (Issued 09-04)

19 7 Reline the Brakes 7 Reline the Brakes Hazard Alert Messages Read and observe all Warning and Caution hazard alert messages in this publication. They provide information that can help prevent serious personal injury, damage to components, or both. WARNING To prevent serious eye injury, always wear safe eye protection when you perform vehicle maintenance or service. ASBESTOS AND NON-ASBESTOS FIBERS WARNING Some brake linings contain asbestos fibers, a cancer and lung disease hazard. Some brake linings contain non-asbestos fibers, whose long-term effects to health are unknown. You must use caution when you handle both asbestos and non-asbestos materials. Reline the Brakes CAUTION Reline the brakes when the lining thickness is 0.25-inch (6.3 mm) at the thinnest point. The rivets or bolts must not touch the drum. Damage to components will result. Figure 7.1 RIGHT WHEEL ROTATION WHEEL ROTATION WHEEL ROTATION CAM BEHIND AXLE CAM IN FRONT OF AXLE LEFT WHEEL ROTATION WHEEL ROTATION WHEEL ROTATION Use the lining material specified by the vehicle manufacturer. This will help to ensure that the brakes perform correctly and meet Department of Transportation (DOT) performance regulations. Always reline both wheels of a single axle and all four wheels of a tandem axle at the same time. Always install the same linings and drums on both wheels of a single axle and all four wheels of a tandem axle. It is not necessary that the front and rear axles have the same linings and drums. NOTE: The primary linings must be installed onto the primary shoe. The first shoe past the cam in the direction of wheel rotation is the primary shoe. Figure 7.1. The primary shoe can be either at the top or the bottom position, depending on the location of the cam. If the cam is behind the axle, the top shoe is the primary shoe. If the cam is in front of the axle, the bottom shoe is the primary shoe. CAM IN FRONT OF AXLE Figure 7.1 Installing Linings with Rivets CAM BEHIND AXLE a 1. Check to ensure that the lining and shoe contact faces are clean. 2. Align the rivet holes in the lining with the rivet holes in the shoe. NOTE: Verify that the rivets are the correct body diameter, head size and shape, length and material. 3. Install the rivets into the rivet holes following the correct sequence. Figure 7.2. Meritor Maintenance Manual MM-0440 (Issued 09-04) 15

20 7 Reline the Brakes Figure 7.2 Figure 7.3 Figure a A gap of 0.10-inch (0.25 mm) maximum is acceptable between the shoe and linings along the side and ends of the assembly, except between the double web. A inch (0.64 mm) gap is acceptable between the webs. Figure Install the bolts and lock washers into the bolt holes following the correct sequence. Figure 7.2. Tighten 3/8-inch diameter brass bolts to lb-in or lb-ft ( N Tighten 1/4-inch diameter brass bolts to lb-in or 7-8 lb-ft ( N Oversize Drums CAUTION Do not operate the vehicle with the brake drum worn or machined beyond the discard dimension stamped on the drum. The brake system may not operate correctly if the drums are worn or machined beyond the discard dimension and cause serious personal injury or damage. To compensate for the worn or refaced drums, X (1/16-inch oversize) and XX (1/8-inch oversize) brake linings are supplied by the lining manufacturers a Figure 7.3 Installing Linings with Bolts NOTE: The same procedures must be followed with bolted linings as with riveted linings. New lock washers must be used during installation. 1. Check to ensure that the lining and shoe contact faces are clean. 2. Align the bolt holes in the lining with the holes in the shoe. NOTE: Verify that the bolts are the correct body diameter, head size and shape, length and material. 16 Meritor Maintenance Manual MM-0440 (Issued 09-04)

21 8 Maintenance 8 Maintenance Hazard Alert Messages Read and observe all Warning and Caution hazard alert messages in this publication. They provide information that can help prevent serious personal injury, damage to components, or both. WARNING To prevent serious eye injury, always wear safe eye protection when you perform vehicle maintenance or service. During lubrication procedures, if grease flows from the seal near the camshaft head, replace the seal. Remove all grease or oil from the camshaft head, rollers and brake linings. Always replace linings contaminated with grease or oil, which can increase stopping distances. Serious personal injury and damage to components can result. ASBESTOS AND NON-ASBESTOS FIBERS WARNING Some brake linings contain asbestos fibers, a cancer and lung disease hazard. Some brake linings contain non-asbestos fibers, whose long-term effects to health are unknown. You must use caution when you handle both asbestos and non-asbestos materials. Lubrication Brake Assembly Components Refer to Table C for grease specifications. Table C: Cam Brake Grease Specifications Components Meritor Specification NLGI Grade Grease Type Outside Temperature Retainer Clips O-616-A 1 Clay Base Down to 40 F ( 40 C) Anchor Pins O-617-A 1 Lithium 12-Hydroxy Refer to the grease Rollers, Journals Only O-617-B 2 Stearate or Lithium manufacturer s Complex specifications for the Camshaft Bushings temperature service limits. O Synthetic Oil, Clay Base Down to 65 F ( 54 C) O and 2 Lithium Base Down to 40 F ( 40 C) Camshaft Splines Any of above Refer to above Refer to above Refer to above O-637* 1-1/2 Calcium Base Refer to the grease O-641 Anti-Seize manufacturer s specifications for the temperature service limits. *Do not mix Meritor specification O-637 grease, part number 2297-U-4571, a calcium-base, rust-preventive grease, with other greases. Meritor Maintenance Manual MM-0440 (Issued 09-04) 17

22 8 Maintenance Camshaft Bushings Meritor recommends that you install new camshaft bushings whenever you install a new camshaft. Lubricate through the fitting on the bracket or spider until new grease flows from the inboard seal. Rollers and Anchor Pins When you disassemble the brake, or when necessary, lubricate the anchor pins and rollers where these parts touch the brake shoes. Do not allow grease to contact the area of the roller that touches the camshaft head. Figure 8.1. Figure 8.1 Lubricate here only. Lubricate entirely. BRAKE SHOE ROLLER Figure 8.1 Do not lubricate here. BRAKE SHOE ANCHOR PIN c 18 Meritor Maintenance Manual MM-0440 (Issued 09-04)

23 8 Maintenance Slack Adjuster Inspect and lubricate the automatic slack adjuster according to one of the schedules below. Use the schedule that requires the most frequent inspection and lubrication, and whenever you reline the brakes. Refer to Table D for grease specifications. Vehicle manufacturer s schedule Fleet s schedule Every six months A minimum of four times during the life of the linings Table D: Automatic Slack Adjuster Grease Specifications Components Meritor Specification NLGI Grade Grease Type Outside Temperature Automatic Slack Adjuster O-616-A 1 Clay Base Down to 40 F ( 40 C) O Synthetic Oil, Clay Down to 65 F ( 54 C) Base O and 2 Lithium Base Down to 40 F ( 40 C) Clevis Pins Any of above Refer to above Refer to above Refer to above O-637* 1-1/2 Calcium Base Refer to the grease O-641 Anti-Seize manufacturer s specifications for the temperature service limits. *Do not mix Meritor specification O-637 grease, part number 2297-U-4571, a calcium-base, rust-preventive grease, with other greases. Anti-Seize Compound Use anti-seize compound on the clevis pins of all automatic slack adjusters. For a conventional automatic slack adjuster, use anti-seize compound on the slack adjuster and camshaft splines if the slack adjuster gear does not have a grease groove and holes around its inner diameter. Intervals Applications On-Highway Q Plus, Cast Plus and Q Series brakes, for every 100,000 miles ( km) or every six months, whichever comes first. P Series brakes, for every 50,000 miles ( km) or every six months, whichever comes first. Off-Highway At least every four months when you replace the seals and reline the brakes. Every two weeks during the first four-month period, inspect for hardened or contaminated grease and for the absence of grease to help determine lubrication intervals. Lubricate more often for severe-duty applications. Specialty Lubricate every six months, at each reline or every 10,000 miles ( km). Adjust the Brakes NOTE: Adjust the wheel bearings before you adjust the brakes. Clean, inspect and adjust the brakes every time you remove a wheel hub. Adjust the brakes when the chamber stroke exceeds CVSA limits. Refer to Section 6. Meritor Maintenance Manual MM-0440 (Issued 09-04) 19